A keyboard which is used as an input device of a personal computer or the like may be used at a dark place. It is required that a keyboard can allow an operator to know a position of a keybutton even in a case where the keyboard is used at a dark place.
Patent Literature 1 discloses a keyboard which guides light from a light source provided on a substrate to a keytop by a prism (light guide member) provided on the inside of the keybutton and illuminates the keytop.